ptuomov

Frequency of refilling the tank was higher than for my turbo 928 for sure. Maybe it was the exhaust note that made me run it differently, or the paddle shift manual. The turbo 928 I cruise at pretty low rpm as it would just take off without any gear changes at the press of the pedal. With the M5 V10 it was a more involved process. Plus I was younger then...

Strosek Ultra

Everybody except myself calm down with age.
Åke

Carl Fausett

Agreed. Generally accepted engine building and design practice is to use the lowest spring pressures possible that will control the valve. No more.

When we had valve float at 6600 rpm, I went up 4 pounds and solved the problem. No more than needed.

GregBBRD

No question that longer duration, with the same lift, is going to be an easier task for the valve train....the ramps are more gentle (on a properly designed cam.)

I think the assumption was that cams with more than 240 degrees of duration (at .050") would be used in engines that were going to turn more than 7,000 rpms, which this one article considered the practical limit for Beehive springs.....thus the 240 degrees and 7,000 rpm limit for Beehive use. (Note that this is not my specification, but only what I read.)

It might be worth mentioning that valve train weight has a huge affect on what is required for spring pressure. The reduction of the weight of the retainer when using a Beehive spring is moot, when one is using a stock hydraulic lifter....a veritable lead weight.

I use no where near 110lbs on the valve seat in my engines....and allow clients to spin them to 7200 rpms, with no issues.

The point is, that when one is talking about only using the minimum spring required to so a task, the spring requirement is relative to the job that needs to be done.

ptuomov

7,000 rpm limit may have been on some specific pushrod engines, like the Nextel Sprint / NASCAR engines without rpm chip or restrictor plate, or on the LS7 engine whcih runs beehives from the factory. It makes sense that when a two-valve engine with big valves, high valve lifts, and heavy pushrods needs to spin 8k, 9k, or 10k, double or triple valve springs are used today. It's for the four-valve DOHC engines where I think beehives are in the process of driving out the double spring to extinction.

Using the light-weight VW lifters is a no brainer, if one is swapping cams. Beehive weight savings are smaller, but also meaningful. I think one should go beehives if one has to swap springs.

Going titanium retainer on a beehive spring while running hydraulic lifter, even if a light-weight VW lifter, doesn't have a good return on investment. The steel retainer on a beehive weighs basically nothing already. Ake's return on investment may be an exception since he makes his own titanium retainers.

I completely agree that one should run the minimum required amount of spring on these engines. Excessive valve spring load will hurt both power and reliability. That's why I ran the turbo car with stock S4 springs (worked just fine with S4 cams up to the factory red line) and with bigger cams I'm trying to run it with Mod-Ford springs reset to _lower_ loads than standard PAC Mod-Ford springs. If everything else is working as intended in a N/A or turbo 928 4-valve engine, 110 lbs seated load seems very high to me. The load on the nose should match what the cam requires at the redline rpm chosen, so it's again in my opinion not a situation that lends itself to "one size fits all" springs.

GregBBRD

I've stopped using the VW lifter.

Because the Beehive spring is smaller at the top, there is more potential/induced retainer wobble, especially on the traditional German design keepers and retainers (where the ends of the keepers contact each other and do not fit tight into the valve.)

A titanium retainer is not happy, in this application.....even with dual springs.

110+ pounds, on the seat, is crazy talk, to me....but different people have different ways of doing things.

ptuomov

If the lifter hardness is a concern, then it's even more important to run the lightest possible valvetrain within reason, because that allows one to run lower spring loads.

It's my understanding that the "wobble" is less of an issue with beehives than with cylindrical springs (single or double). Because of its shape, beehive spring is inherently more stable and wants to move the valve stem less. This is a large offsetting effect to the effect of the retainer diameter. I forgot which major car factory studied this, but the result from memory was that the valve guides wear less and they could use smaller diameter valve stems with beehives. In net, I believe that the valve stem/lock/retainer stability is a net positive for beehives over cylindrical springs.

Opinions vary on whether the floating vs. locking valve stem / lock interface is a positive or negative. My understanding is that the floating interface (such as that in the stock S4 head where the two lock halves bind to each other with no gap) has the benefit of better durability of the valve-seat-to-valve contact area. The rotating valve evens out any wear or impact of any impurities. In contrast, the floating valve stem / lock interface is weaker at the valve stem side. For a performance engine with aggressive cams, it's my opinion (not a fact) that when picking between these two poisons one should pick the valve locks that don't allow the valve to rotate and instead lock the valve by leaving a small gap between the lock halves.